This invention relates to folding methods applied to a typical commercial microwave popcorn bag, approximately 14 cm by 30.5 cm (5 1/2 by 12 inches) when unfolded, to control linear expansion and permit better popping in a small microwave oven (less than 1 cubic foot capacity) having a rotating turntable.
A commercially available microwave popcorn bag, when popped in accordance with the instructions, will usually expand to a length larger than an interior dimension of the microwave oven, causing one of the outer flaps to strike one of the sides of the oven. The turntable then skews the bag off the center of the turntable, away from the centrally focused beams of the oven, resulting in less even heating and in less corn being popped. Also, the lower applied heat produces inferior, tougher popcorn. Thus, the current fabrication of commercial microwave popcorn bags doesn't properly accommodate the vast number of small microwave ovens that exist in the world today.
Folding methods were developed for a typical commercial microwave popcorn bag to retard its lateral expansion and enable it to remain centered in a small (one cubic foot or less) microwave oven while the bag is being expanded by the gases of the popping corn. This is particularly true for small microwave ovens having turntables, where the turntable tends to drag the bag off its central area if the unfolding bag flaps strike the oven wall. These methods consist of folding each outer flap of the bag (1 and 2 of FIG. 3) over on itself at least twice, and then against the central body as shown in FIG. 5; folding each flap over on itself multiple times, and against the central body, FIG. 9; folding the two corners diagonally in to the centerline of each of the two flaps, and folding them against the central body, FIG. 13, to retard the bag's lateral expansion during the popping process. The machinery to effect these folds is not a part of this invention.